Opacifying substance for enamels, glasses, and the like



Patented Mar. '15, I932v IGNAZKREIDL, or IENNA, AUSTRIA OPACIFYING SUBSTANCE FOR ENAMELS, GLASSES, ANDITHE'LIKE No Drawing. Application filed December 20, 1927, SerialNo. 241,464, and; in Austria January 4, 1927.

This invention relates to an opacifier for pound in the proportion most favourable for ing agent.

products obtained in this way is extremely opacifying, that is to say, for 'twomolecules SiO one molecule metallicoxide. In this proportion the metallic oxide enters into the compound and directly produces the opacify- The opacifying power of the great.

The alkali or alkaline earth may be intro duced into the aluminium silicate com- 5 pound by treating the latter with oxides, hy-

like'ofthe alka droxides, carbonates and the lies or alkaline earths or mixtures thereof.

When use is made of caustic alkalies, the combining can be effected by bo llng the alkali solution with the clays or artificially prepared products; when carbonates are use preferably by fusing together.

Ewample Kaolin is introduced while stirring, into a boiling 30% solution of caustic soda, the amount of caustic soda to be employed being so calculated that one molecule Na O corresponds to two molecules SiO In this exothermic process, the Na O enters intothe kaolin, while the water of the caustic soda solution is evaporated, The reaction product obtained in this Way, if not sufliciently dry, is dried. In this drying the reaction product may also be exposed to increased tempera tures, in which case however temperatures should be avoided which are higher than the Those aluminium 211- of the product, characteristic for opacifying' purposes, are not present.

What I claim is: 1. An enamel containing an opacifier comprising a silico-aluminate compound of an alkali-forming metal derived fromthe treatment of kaolin with an alkali-forming metal I oxide and wherein the aluminium oxide and the silicic acid are present substantially in the same proportionas in the kaolin.

prising a'silico-aluminate compound of an alkali-forming metal derived from the treatment of kaolin with an alkali oxide and wherein thealuminium oxide and the silicic acid are present substantially in the same proportions as in the kaolin.- V

3. An enamel containing an opacifier comprising a 'silico-aluminate compound of an alkali-forming metal derived from the treatment of clay with an alkali-forming metal oxide, and wherein the aluminium oxide and the silicic acidv constituents-are present substantially in the same proportions as I in the clay.

j 4;. An enamel prising a silico-aluminate compound of an alkali-forming metal derived from the treat-v "ment of clay with an alkali oxide and where-3 in the aluminium oxide and the silicic acid same proportions as in the clay. In witness whereof I have hereunto signed usual annealing temperatures'of the enamels,

i. e. about 800 C. At temperatures higher than these, the physical properties (colloid) containing an opacifi-er comd constituents are present substantially in the 2. An enamel contalnlng an opaclfier com- 

